Multicasting and broadcasting refers generally to sending information to a plurality of receivers. In multicasting and/or broadcasting data, a system may use macrodiversity, which refers to a type of transmission in which a plurality of base stations synchronously transmit the data over the same frequency, using the same waveform, and using about the same framing parameters. A network employing macrodiversity is sometimes referred to as a single frequency network (SFN).
At a receiver, such as a client station, the macrodiversity may be exploited by the receiver. For example, the multiple versions of the same signal received from the multiple base stations may be combined to produce a signal with improved signal strength at the receiver. The gain achieved by combining these multiple versions of the same signal is often referred to as “macrodiversity gain.”
One standard that supports the multicasting and/or broadcasting of data is IEEE 802.16. As used herein, IEEE 802.16 refers to one or more specifications, such as the Institute of Electrical and Electronic Engineers (IEEE) Standard for Local and metropolitan area networks, Part 16: Air Interface for Fixed Broadband Wireless Access Systems, 1 Oct. 2004, the IEEE Standard for Local and metropolitan area networks, Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems, 26 Feb. 2006, and subsequent revisions and additions to those standards. Pursuant to IEEE 802.16, multicast and/or broadcast data may be transmitted to client stations using a region of an Orthogonal Frequency Division Multiple Access (OFDMA) data frame referred to as the Multicast and Broadcast Services (MBS) region.
FIG. 9 depicts an example of OFDMA frames 910A-D used in connection with an MBS transmission consistent with IEEE 802.16. The OFDMA frames 910A-D includes data regions, such as MBS regions 912A-D, transmitted in a downlink from a base station to a client station. These data regions represent one or more OFDMA symbols (or simply symbols) carrying the content (e.g., packets) of the multicast and broadcast service. When macrodiversity is used, each of the base stations synchronously transmit an MBS region using about the same waveform, at the about same frequency, and at about the same time (e.g., the first symbol of an MBS region is transmitted at about the same time at each of the base stations). In accordance with IEEE 802.16, each of the MBS regions 912A-D is described by an MBS MAP 914A-D, so that an MBS MAP describes an MBS region. The size and location of the MBS regions and the composition of the MBS MAPs is described in downlink (DL) MAPs 916A-D and, more particularly, in messages (also referred to as “information elements”) included within some of the downlink MAPs 916A-D. These information elements are referred to in IEEE 802.16 as an “MBS MAP IE”. This information from the DL-MAP may be used by the client station to decode one or more of the MBS MAPs 914A-D, which describes how to decode (e.g., receive, demodulate, correct for errors, and the like) a corresponding MBS region 912A-D.